This invention relates to an elastomeric seal device for a threaded or grooved shaft within a housing. In one embodiment, this seal is interposed between a ball bearing nut and its threaded shaft operating within a hydraulic cylinder.
Ball bearing nuts and their associated screws present unusual sealing requirements. First, the sealing surface on the screw is defined by a thread which extends both axially and circumferantially of the screw. Because of the space required for greater than the outside diameter of the screw, thus presenting a large area to be sealed and exposing such a seal to substantial shearing forces. Additionally, the screw, having both translational and rotational motion relative to the ball bearing nut requires not only the use of a low friction material, but that such a seal be capable of withstanding substantial forces which are not uniformly applied to a single direction. Finally, it may be desirous of encapsulating this unit within a cylinder and using the nut as a hydraulic piston responsive to fluid pressure to assist reciprocation as controlled by rotary movement of the screw.